Simulation of helium exhaust in JET and ITER

Abstract

The problem of helium exhaust is studied using the integrated code package Combined Code Numerical Utility for Tokamaks (COCONUT): the 2D scrape-off layer code EDGE2D/NIMBUS is coupled with the 11/2D plasma transport codes JETTO and SANCO to allow consistent modelling of the entire plasma cross section. The code is first benchmarked against JET experiments in order to determine the radial helium transport in the core and in the SOL. The findings are then applied in predictive modelling of the ITER design. The results of the simulations are expressed in terms of confinement times and enrichment. For JET, we obtain values consistent with direct experimental measurements. The predictions for ITER are seen to be very sensitive to the model assumptions for the scrape-off layer.